1. Field of the Invention
This invention relates to a spectrometer, which is used with an electromagnetic wave intensity detector and with a liquid cell, a flow cell or a holder of a specimen, and which measures a specimen's absorbance or reflection of electromagnetic wave at a particular wavelength and/or a particular range of wavelength. Such spectrometer includes instruments, which are usually classified as a UV spectrophotometer, a visible light spectrophotometer, an IR spectrometer, an atomic absorption spectrometer, a mass spectrometer and an electron spin resonance spectrometer.
The most widely used spectrometer is a UV-visible light spectrophotometer, which is called spectrophotometer in this specification.
2. Description of Related Art
A spectrophotometer has, as the essential parts, a light source portion and a spectroscope portion which separates light into its spectral component. In the light source portion, generally, lamps and a light source changing mechanism are set on a frame. In the spectroscope portion, monochromator such as grating or prism and wave length changing mechanism, is set on a frame.
Usually, such a frame is made of metal, and is fabricated into its particular shape by either a sheet metal processing, a metal cutting processing or a casting. Because metal is not easy to work, a frame can not be fabricated with the accuracy that a spectrophotometer demands for its frame. Thus, fabricating a spectrophotometer with such frame, requires many parts and requires further adjustment after the parts are installed on the frame.
As a result, it takes a long time for fabricating the frame and adjusting the spectrophotometer during assembly. Thus, the quality control of a spectrophotometer is difficult and costly.
Some frame improvements have been made in order to overcome above mentioned difficulty. FIG. 8 shows an example of a conventional spectrophotometer. A frame 51, which is made of metal provides the complete spectrophotometer's base. A lamp and mirror 53 and monochromator mechanism 54 are installed on the frame 51. A cover 52 is provided for covering the complete spectrometer. This type of spectrophotometer will maintain an accuracy of the position between the parts, so that it is easy to control the quality of a final product. However, because the frame 51 is large and heavy, it is time consuming to install all of the parts on it. Further, making adjustments, checking up and repairing, the light source portion and the spectroscope portion separately, is difficult. Thus, productivity as a whole decreases in the production of such a spectrophotometer.
FIG. 9 shows an other example of a conventional spectrophotometer. A lamp and mirror 53 are installed on a frame 55, which is made of metal. The spectroscope parts and mechanism are installed on a separate frame 56, which is also made of metal. The frame for the light source portion 55 and the frame for spectroscope portions 56 are installed on a single main frame 51, which is also made of metal. A cover 52 is provided for covering the complete spectrophotometer. The necessary parts are easy to install on both frames of this type of spectrophotometer. Further making adjustments, checking up, and repairing can be done separately, for each portion. However, when each portion is installed on the main frame 51, it is necessary to secure each portion at a precise position, and to connect electrical wires to each other. Moreover, it is difficult to maintain the precise positioning with accuracy during a long period of time.